mxcl/homebrew — pull request #23563 by manphiz (2013-10-24 23:18:09+00:00)
Title: Make stdenv handling less intrusive.

* Use "-I" instead of "-isystem" in $CPPFLAGS, as the latter is only
supported in GCC/Clang, while the ENVVAR is used in other situations
and may break building.

* Don't encode "-Qunused-arguments", as this is only supported in Clang
and will break building when C/C++ compiler is switched during the
process, e.g. building gcc. The warning is harmless without
"-Werror".